Fagopyrum tataricum, also known as Tartary buckwheat, green buckwheat, ku qiao, or bitter buckwheat, is a domesticated food plant in the genus Fagopyrum in the family Polygonaceae. With another species in the same genus, common buckwheat, it is often counted as a cereal, but unlike the true cereals the buckwheats are not members of the grass family. Thus they are not related to true wheat. Tartary buckwheat is more bitter, but contains more rutin than common buckwheat. It also contains quercitrin. Rutin and quercitrin have been proven effective in detoxification, especially in prevention of liver damage or liver inflammatory injury. 
Tartar buckwheat was domesticated in east Asia, and is also cultivated in Europe and North America. While it is an unfamiliar food in the West, it is common in the Himalayan region today, as well as other regions in Southwest China such as Sichuan province.
The plant has been cultivated in many parts of the world though when found among other crops it is considered a weed.

Buckwheat Tea is Caffeine-Free

While buckwheat hull tea does not beat green tea in terms of antioxidant power (as demonstrated by a Polish study published in the International Journal of Food Properties), it nevertheless provides plenty of antioxidants, including rutin and vitexin. Rutin, in particular, has been credited with a number of health benefits, including improved blood flow and prevention of varicose veins and leg edema. It may also help improve metabolic conditions such as insulin resistance, pre-diabetes, and polycystic syndrome (PCOS).